Abdominal Imaging Modalities in Emergency Medicine

Modality	Plain Radiography (X-ray)	Ultrasound	CT Scan	MRI
Modality	X-RAY	ULTRASOUND	CT SCAN	MRI
Availability	Excellent Fast and widely available	Excellent Readily available, bedside capable	Good Usually available in ED	Limited Availability and scan time constraints
Radiation	Low Minimal radiation exposure	None No ionizing radiation	High Significant radiation exposure	None No ionizing radiation
Best For	• Suspected bowel obstruction • Free air (pneumoperitoneum) • Foreign bodies • Initial screening	• Gallbladder pathology • Kidney evaluation • Pelvic organs • Pregnancy-related conditions • Pediatric patients	• Appendicitis • Diverticulitis • Pancreatitis • Vascular emergencies • Trauma evaluation	• Pregnant patients (when US inconclusive) • Suspected appendicitis in pregnancy • Soft tissue detail • Vascular imaging without contrast
Advantages	• Fast acquisition • Low cost • Widely available • Minimal radiation • No contrast needed	• No radiation • Real-time imaging • Bedside capability • Safe in pregnancy • Cost-effective	• High spatial resolution • Broad anatomical coverage • Excellent detail • Widely diagnostic • Quick acquisition	• Excellent soft tissue contrast • No radiation • Multiplanar imaging • Superior tissue characterization
Disadvantages	• Low sensitivity for many conditions • Limited diagnostic yield • Poor soft tissue detail • Overlapping structures	• Operator dependent • Limited by bowel gas • Body habitus limitations • Limited penetration	• Radiation exposure • Often requires IV contrast • Cost • Contrast allergies/contraindications	• Limited availability • Long scan times • High cost • Contraindications (pacemakers, etc.)
Key Limitations	• Cannot rule out most acute conditions • Limited to obvious pathology • Poor sensitivity for inflammation	• Bowel gas interference • Obesity limitations • Skill-dependent interpretation	• Kidney function concerns with contrast • Pregnancy considerations • Artifact from metal	• Not suitable for unstable patients • Motion artifacts • Limited emergency availability
Special Considerations	• Often first-line screening • May guide further imaging • Useful for follow-up	• Preferred in pregnancy • Excellent for pediatrics • Point-of-care capability	• Often the "workhorse" modality • May require pre-medication • Hydration considerations	• Reserved for specific indications • May need sedation • Screening questionnaire required

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